In some internal combustion engines, a burner apparatus is provided upstream of an exhaust treatment apparatus (a catalyst and the like) in an exhaust passage. In this case, heating gas generated by the burner apparatus is utilized to increase an exhaust temperature. The exhaust treatment apparatus is thus heated to promote warm-up thereof. The burner apparatus typically ignites and combusts fuel added into the exhaust passage to generate heating gas containing flame. A small-sized oxidation catalyst may be provided in the exhaust passage to reform or combust the added fuel.
For example, an apparatus described in Patent Document 1 intermittently supplies fuel directly to a small-sized oxidation catalyst in the exhaust passage to intermittently generate flame downstream of the small-sized oxidation catalyst.
Preferably, during warm-up after starting of an internal combustion engine, the small-sized oxidation catalyst, located on an upstream side, is activated earlier than the exhaust treatment apparatus, located on a downstream side. Thus, preferably, heating gas is more positively supplied to the small-sized oxidation catalyst than to the exhaust treatment apparatus. On the other hand, preferably, after the small-sized oxidation catalyst is activated, heating gas is more positively supplied to the exhaust treatment apparatus than to the small-sized oxidation catalyst to promote warm-up of the exhaust treatment apparatus.
However, in general, the position of an ignition point for the added fuel is not subjected to any control. Thus, even if heating gas is desirably positively supplied to the small-sized oxidation catalyst, the hating gas may be actually positively supplied to the exhaust treatment apparatus or vice versa. Hence, efficient warm-up of the small-sized oxidation catalyst and the exhaust treatment apparatus is difficult.
An object of the present invention is to provide an internal combustion engine that allows the small-sized oxidation catalyst and the exhaust treatment apparatus to be efficiently warmed up.
Citation List
Patent Literature
    PTL 1: Japanese Patent Laid-Open No. 2010-59886